I wish I had that problem. I'm not a big modern Rolex fan (LOVE older Rolex references and wish they'd do tribute watches even though they'd bankrupt and I'd resort to becoming a male stripper to get them), but I have to say BLNR here. Something about the IWCs leave me wanting a bit. I'm also not a fan of the size of the size, though compared to other references it's not as bad, and I don't like power reserve registers on watches (OK, I like anything on a Lange, but generally speaking).
As @robw noted, I would also consider waiting for the BLNR if that's what it takes to save $1000 on the BLNR. Also as @tigerpac noted, I have seen some on the grey market recently that were discounted. And as @tricky noted, you can change to a strap on the Speedmaster. In fact you can even lose the bracelet on the BLNR from time to time. I was looking online and someone had a Camille Fournier custom made strap that was made out of sailcloth on a dive watch. If you created your own strap on their site you can even choose the strap thickness which is nice option.
Neither watch is truly rare. I think that we need to take the rarity factory with a grain of salt with the idea that the rarity of sightings in the wild is somewhat dependent on where you live. Rolex is probably the mostly commonly seen "Nice watch." However, at least in my region of the States I've yet to see another person wearing a BLNR. I'm sure if I went to LA, NYC, Vegas, or even Boston etc...I'd see some over the course of a few days. I find this to be true of Pateks, APs, VC. Lange, I'm far more likely to see several of those in just a few days in a big city than I am in my local area over the course of a few months.
So depending on where Ari lives, he may or may not see some BLNRs or Portugusers in any given month.
Personally, I never mind seeing someone wearing the same as me. As I've said before, I just think to myself, "Damn, that guy has good taste!"